56 J. A. Leach : 



A visit shortly after this to the Royal Park railway cutting 

 showed where the water had trickled over the edge of a hard 

 iroi'stone layer. It had carried down the sand and clay mixture 

 under it. Some of this liquid mud had then fallen a short dis- 

 tance from a convenient hard point. Here it had built up two 

 little mud pillars (stalagmites'?) of the deposits from the liquid 

 mud which had trickled down. 



In all the railway cuttings in the coastal plain material round 

 Melbourne, this scooping out of the softer material under the 

 harder bands can be clearly seen. That also is one of the 

 features so noticeable in many of the good views of the Grand 

 Canyon of the Colorado. 



In each of the numerous cases of canyon formation now going 

 on around Melbourne that I have visited, the same phenomena 

 have been noticed. In a few cases, even where wearing away 

 is proceeding very rapidly, no water falls over. All the water 

 causing such serious loss to the land owners simply trickles down 

 over the softer material. This, when wet, becomes liquid mud. 

 So the solid earth is really melting or flowing away. 



In one case at North Essendon a brick wall, with a large V 

 opening for the water to flow in, was built across a gutter lead- 

 ing from a road to the adjacent Moonee Ponds Creek. This 

 rejuvenated stream had deepened its bed over 20 feet. The trickle 

 of water from the gutter soon wore the soft alluvium away, and 

 formed a deep canyon. 



The water then worked under the brick wall, which has novv been 

 left high and dry across a considerable canyon, with the water 

 flowing many feet below the lower portion of the brickwork. 

 This alarming result has been accomplished in a very short time 

 by the very small quantity of water that flows, only after rain^ 

 in a gutter at the side of the road. 



The harder Silurian bedrock, of course, would not be worn 

 away so readily, so that it is only in the softer material of the 

 coastal plain, or other recent deposits, that this very rapid 

 weathering is going on. Still, it is being done by an insignifi- 

 cant quantity of water. 



In the canyons at Coburg, the side of the gorge is coated 

 with a very tine powdery material. This has been left there 

 when the water, which in wet weather formed a film over it, 



